Achieving ultimate noise tolerance in quantum communication

TL;DR

This paper introduces an ultrafast optical platform for quantum communication that significantly reduces channel noise, enabling high-rate, daytime quantum key distribution with enhanced noise tolerance.

Contribution

The authors experimentally demonstrate ultrafast optical filtering that approaches a single spectro-temporal mode, dramatically improving noise tolerance in quantum communication.

Findings

Achieved up to 1200-fold noise reduction with ultrafast filtering.

Enabled quantum communication in bright fibers during daytime.

Demonstrated a 1-ps temporal gate for noise filtering.

Abstract

At the fundamental level, quantum communication is ultimately limited by noise. For instance, quantum signals cannot be amplified without the introduction of noise in the amplified states. Furthermore, photon loss reduces the signal-to-noise ratio, accentuating the effect of noise. Thus, most of the efforts in quantum communications have been directed towards overcoming noise to achieve longer communication distances, larger secret key rates, or to operate in noisier environmental conditions. Here, we propose and experimentally demonstrate a platform for quantum communication based on ultrafast optical techniques. In particular, our scheme enables the experimental realization of high-rates and quantum signal filtering approaching a single spectro-temporal mode, resulting in a dramatic reduction in channel noise. By experimentally realizing a 1-ps optically induced temporal gate, we show that ultrafast time filtering can result in an improvement in noise tolerance by a factor of up to 1200 compared to a 2-ns electronic filter enabling daytime quantum key distribution or quantum communication in bright fibers.